Although the term "two-phase pumping" is commonly used to designate energy supply to a fluid consisting of a liquid phase and of a gas phase, we will use in the description hereafter the term "compression", that is better suited to designate energy transfer to a compressible two-phase fluid, especially when it is characterized by a high gas/liquid volume ratio (GLR under real temperature and pressure conditions).
Various devices, some examples of which are mentioned hereafter, allow to compress a two-phase fluid consisting of a gas and of a liquid, and possibly of solid particles:
a series of single-phase machines (consisting at least of a pump and of a compressor) preceded by a separation system. This production mode leads to bulky and expensive compression installations, PA1 using radial impellers to directly compress a gas-liquid mixture. These impellers are limited to gas ratios generally lower than 20%. This limit can be extended to about 30% by using radio-axial impellers and beyond with axial impellers, PA1 positive-displacement machines (reciprocating, screw, membrane machines) allow to obtain a good compression efficiency for a two-phase mixture. On the other hand, they are very ill-suited to the high volume flow rates that characterize applications with high gas ratios, PA1 rotodynamic devices with helico-axial impellers, such as those described in the claimant's patent FR-2,665,224; the latter are particularly well-suited for compression of a two-phase mixture having a high volume flow rate. On the other hand, the low manometric head produced by each impeller does not allow to obtain very high compression ratios when the GLR is above 20. Furthermore, the efficiency of these impellers is lower than the efficiency of single-phase machines and it tends to decrease when the input pressure decreases, PA1 devices using dynamic separators upstream from a dry gas compressor, such as the gaseous fluid compressor associated with a gas-liquid separator described in patent application WO-87/03,051. PA1 at least one alternating compression-pumping section, suited to impart a pressure value to an essentially liquid fluid or to an essentially gaseous fluid, the compression-pumping section comprising at least one line for delivering an essentially liquid phase, at least one line for delivering an essentially gaseous phase, at least one line intended for discharge of a gas that has acquired a certain energy after passing through the system, and at least one line intended for discharge of a liquid that has acquired a certain energy after passing through the compression-pumping section, PA1 at least one pumping section selected to impart energy to an essentially liquid fluid, the pumping section comprising at least one line for delivering an essentially liquid phase and at least one line for discharge of the liquid phase pumped, PA1 at least one device for separating the various phases that constitute the multiphase fluid, the separation device being connected to a multiphase fluid delivery line and to the line intended for discharge of the liquid coming from the alternating compression-pumping section, the device comprising at least one gas phase discharge line and at least one liquid phase discharge line, PA1 the separation device is provided with means (C.sub.L) allowing to detect the gas-liquid interface level of the fluid introduced in the separation device, PA1 means (Vgi, Vli) allowing to control the flow rate of the liquid or gas phases in the Bvarious lines, PA1 control means allowing to vary the state of the flow rate control means so as to shift the compression section from an operating mode suited to gas to an operating mode suited to liquid and vice versa. PA1 a helical line intended to separate the liquid droplets from the gas phase, PA1 a series of disks mounted on the shaft, the shaft extending in the separator. PA1 a) separating the multiphase fluid into an essentially gaseous phase and an essentially s liquid phase, PA1 b) determining the liquid or liquid-gas interface level L in the separation device, PA1 c) comparing level L with a threshold value L.sub.0, PA1 d) level L is permanently controlled, PA1 at least one alternating compression section, suited to impart a pressure value to an essentially liquid fluid or to an essentially gaseous fluid, the compression section comprising at least one line for delivering an essentially liquid fluid, at least one line for delivering an essentially gaseous fluid, at least one line intended for discharge of a fluid that has acquired a certain energy value by passing through the compression section and at least one line intended for discharge of an essentially liquid fluid, PA1 means allowing to determine the nature of the fluid flowing into the system, these means being arranged upstream from the system, PA1 means allowing to control the flow rate of the liquid or of the gas, PA1 control means allowing to vary the state of the flow rate control means so as to shift the compression section from an operating mode suited to gas to an operating mode for liquid and vice versa. PA1 a) determining the nature of the fluid to which energy is to be imparted, PA1 b) sending the fluid, whatever its nature, to an alternating compression-pumping section, PA1 c) adjusting, during stage b), the alternating compression-pumping section to fluid compression when the fluid is essentially gaseous or to fluid pumping when the fluid is essentially liquid. PA1 reduction in the number of machines in relation to rotodynamic single-phase and multiphase machine, as well as size and weight reduction in relation to positive-displacement machines, PA1 power consumption reduction in relation to rotodynamic multiphase machines.